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-   -   Engine alignment & thrust angle (https://www.rcuniverse.com/forum/kit-building-121/6428749-engine-alignment-thrust-angle.html)

dlan 09-29-2007 02:05 PM

Engine alignment & thrust angle
 
I need to know how critical the proper angle for engine mounting. I am building a Tiger60 and using an OS FS 91.
the plan calls for 2 degrees down and 2 degrees to the right for alignment. Not sure I understand why or what impacts
it will have on flight characteristics. Can someone explain or point me to information on this topic.

Thanks [8D]

Funkerdelicuk 09-29-2007 02:38 PM

RE: Engine alignment & thrust angle
 
you need some down thrust on most models.. the side thrust is to alow the tork of the prop when the engine reves.. If you look at your car you can see it pull to one side when you rev it up.. its the same on model engines. if you put the rong way and too mutch when you open up the throtle it will pull to one side.. i think you need left had thrust.. if you make it so you can ajust it with washers you can find out how thew model performs

Campgems 09-29-2007 09:14 PM

RE: Engine alignment & thrust angle
 
Dlan, it is always good to go with the kit recomendations. The down thrust gives a bit more prop wash over the wings and also gives a slight tug down on the nose. The Right thust reduced the tendcy to yank left when you accelerate for take off. Notice I said reduces it. I am flying a Mag 91 FS in a 4*60, and if you punch it taking off, you are going to end up going off the left side of the runway. If you ease on the throttle, you suddenly find youself flying. The 4* usese 0 and 0 for thrust but every bird is different. 1 and 1 isn't much, but I would still build to the kit.

One of the guys at the field built an "old" scale kit which called for 7R and 4 down. He has a lot of experience building models as well as full sized and he decided to go 0 and 0. He almost lost it on the first flight. Now he has the 7 and 4. looks funny, but it sure does fly good like that.

Don

dlan 09-29-2007 11:06 PM

RE: Engine alignment & thrust angle
 


ORIGINAL: Campgems

Dlan, it is always good to go with the kit recomendations. The down thrust gives a bit more prop wash over the wings and also gives a slight tug down on the nose. The Right thust reduced the tendcy to yank left when you accelerate for take off. Notice I said reduces it. I am flying a Mag 91 FS in a 4*60, and if you punch it taking off, you are going to end up going off the left side of the runway. If you ease on the throttle, you suddenly find youself flying. The 4* usese 0 and 0 for thrust but every bird is different. 1 and 1 isn't much, but I would still build to the kit.

One of the guys at the field built an "old" scale kit which called for 7R and 4 down. He has a lot of experience building models as well as full sized and he decided to go 0 and 0. He almost lost it on the first flight. Now he has the 7 and 4. looks funny, but it sure does fly good like that.

Don
Thanks Campgens! I understand now with the way you have explained it. I will do as the kit suggested!

tstotts 10-03-2007 03:59 PM

RE: Engine alignment & thrust angle
 
Right Thrust. Plane tends to torgue the plane to the left. Left thrust would worsen that.....

MinnFlyer 10-03-2007 05:37 PM

RE: Engine alignment & thrust angle
 
You shouldn't need to worry about it. On the Tiger, the thrust should be built into the firewall.

I may be wrong - been a long time since I built one.

If it's not built in, don't worry about getting it perfect. The "2 Degrees" is pretty much a "Ball Park" figure

dlan 10-03-2007 09:23 PM

RE: Engine alignment & thrust angle
 


ORIGINAL: Campgems

Dlan, it is always good to go with the kit recomendations. The down thrust gives a bit more prop wash over the wings and also gives a slight tug down on the nose. The Right thust reduced the tendcy to yank left when you accelerate for take off. Notice I said reduces it. I am flying a Mag 91 FS in a 4*60, and if you punch it taking off, you are going to end up going off the left side of the runway. If you ease on the throttle, you suddenly find youself flying. The 4* usese 0 and 0 for thrust but every bird is different. 1 and 1 isn't much, but I would still build to the kit.

One of the guys at the field built an "old" scale kit which called for 7R and 4 down. He has a lot of experience building models as well as full sized and he decided to go 0 and 0. He almost lost it on the first flight. Now he has the 7 and 4. looks funny, but it sure does fly good like that.

Don
BTW - hows that Mag 91 treating you? I was luck to get the OS 91, it came in a P40 that I got a smokin deal on. Prior to that I was going
to get the Mag FS 91. I have been happy with Magnum so far...

dlan 10-03-2007 09:26 PM

RE: Engine alignment & thrust angle
 
From what I have been told my radio can also compensate for it too. I have a Futaba 7C. I really more concerned with understanding the concept and I thank you all for
making that possible. My apologies if I "hijacked" the thread for a bit[&o]

Deadeye 10-04-2007 08:46 AM

RE: Engine alignment & thrust angle
 


ORIGINAL: dlan

From what I have been told my radio can also compensate for it too. I have a Futaba 7C. I really more concerned with understanding the concept and I thank you all for
making that possible. My apologies if I "hijacked" the thread for a bit[&o]
The only way a radio can compensate for right thrust is to adjust the rudder off center...not a good idea, as it will effect everything throughout the flight. Keep it in the firewall, or adjust with shims or washers.


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